#!/usr/bin/env node

const Readable = require('stream').Readable;

let c  = 'a'.charCodeAt(0);


class MyReadable extends Readable{
  constructor(){
    super();
  }


  _read(){
    rs.push(String.fromCharCode(c++));
    if(c>'z'.charCodeAt(0)) rs.push(null); 
  }
}

let rs = new MyReadable();
rs.pipe(process.stdout);
